tracee wilkins tells us what simpson said on the stand today. >> reporter: two girls who did not like each other. they had a number of arguments throughout the school year before this incident happened. these are also two girls who came to school packing knives. in fact, today the prosecution used the deceased's knife to show an example of just how big the knife was that alexis simpson used to kill her. now, the prosecution saying that although these girls did not like each other, and made some bad decisions, one of them took it too far and could spend the rest of her life behind bars. alexis simpson took the stand in her own defense today. simpson, who's out on bond is accused of stabbing and killing her roommate, dominique frazier, over an argument of loud music in their dorm last year. simpson testified she was scared of frazier, who she had had a number of arguments with. in cross-examination, the state prosecutor painted young simpson as a woman who wasn't afraid of conflict. the reality is, you weren't scare of dominique? simpson, i was. you weren't scared of nielha? i was. you'